Abstract HPV-associated cancers are a serious problem among HIV-infected men and women in Russia and the U.S. Developing better approaches to prevent these cancers is an important public health goal for both countries. HPV therapeutic vaccines are a promising approach to treat HIV-infected men and women who have already been exposed to HPV and who have HPV-associated cancer precursor lesions, high-grade squamous intraepithelial lesions. Developing effective therapeutic vaccines against HPV is particularly challenging in HIV-positive people. This study will generate information that will be critical to the development of better HPV therapeutic vaccine strategies for HIV-infected men and women. We will collect information on the HPV types and strain variants most relevant to HIV-infected men and women and use it to design plasmids encoding therapeutic vaccine candidates. We will study tissues, cells in tissue culture and animal models to determine how factors that may affect the local immune response in HIV-infected individuals may also affect HPV therapeutic vaccine efficacy in these individuals. These include the programmed cell death protein (PD-1)/ programmed death ligand-1 (PD-L1) axis, HIV-associated inflammatory proteins and HIV protease inhibitors (PI). The specific aims of the study are: 1. Compare the distribution of HPV genotypes and sequence variation of HPV 16 oncogenes in cervical and anal cancers in Russian and American HIV-infected and uninfected men and women; 2. Compare expression of PD-L1 and PD-1 in HPV-associated cancers, HSIL and in immune cells, in HIV-infected and HIV-uninfected men and women; 3. Characterize HIV-related factors that modulate PD-L1 expression in HPV 16-transformed epithelial cells; 4. Characterize HIV-related factors influencing the transformation phenotype of HPV 16-immortalized epithelial cells; and 5. Measure the immunogenicity and efficacy of HPV therapeutic vaccine candidates in murine models, and measure the effects of HIV PI and PD- 1/PD-L1 binding inhibition on immune response and efficacy. Aim 1 will guide the choice of HPV sequences used for the therapeutic vaccines. Aims 2, 3 and 4 will provide information on factors that might influence the performance of a HPV therapeutic vaccine in the setting of HIV infection, such as PI and PD-1/PD-L1 binding. Aim 5 will use the information collected in aims 1-4 to design the therapeutic DNA plasmids, test their immunogenicity and efficacy in a murine tumor model, and determine the effect of factors shown to be important in Aims 2, 3 and 4. This project will employ the complementary skill sets of a very experienced team of senior and junior Russian and U.S. investigators. There will be extensive exchange between the U.S. and the Russian Federation of people, expertise, specimens and novel reagents to achieve the goals of this project. Together, we believe that this study will have important implications for new approaches to improving the efficacy of HPV therapeutic vaccination in HIV-infected individuals in both countries, and will be critical to reducing the incidence of HPV-associated cancer in this population.